Catalysis



Sept. 5, 1944. A. H. SCHUTTE 7 2,357,694

' CATALYSIS Filed May 25, 1941 5 Sheets-Sheet 2 Sept. 5, 1944. A. H.SCHUTTE CATALYS IS Filed May 23, 1941 3 Sheets-Sheet 3 INVENTOR .flzgwtHenry .fc/zwze BY .iouled catalyst therefrom.

Patented Sept. 5, 1944 CATALYSIS August Henry Schutta Tuckahoq-N. Y.,assignor -i to The Lummus Company, New York, Y., a

corporation of Delaware Application May 23, 1941,8er1al No. 394,823 4Claims. (Cl. 23-288) This invention relates to the transfer of granularmaterials into and out of pressure-tight chambers and more particularlyrelates to an improved apparatus for conveying a granular catalyst in acontinuous stream into and out of a chemical reaction zone without lossor con-" termination of the reactants.v Itis a continuation-in-piart ofthe invention described in my prior application, S. N..302,278, filedNovember 1, 1939. The said prior application has ma tured into PatentNo. 2,268,535. entitled Method of effecting catalysis.

In my previously filed application, I have re- I ferred to the wellknown use of catalysts whereby desired chemical reactions can beaccelerated or can be carried out at lower temperaturesor lowerpressures or can be accomplished in a' more selective manner. Theinvention described therein is concerned with a method of carrying out acatalytic reaction in which boththe catain countercurrent relationthrough a reaction chamber with a continuous introduction ofjreshcatalyst into the reaction chamber and a continuous removal of partiallycontaminated or highest efficiency of reaction is obtained as thereacting products passing to the outlet come in contact with thefreshest catalyst entering the chamber.

Inasmuch as catalytic reactions, particularly in the hydrocarbon field,are carried out at pressures other than atmospheric and inasmuch as lossof the reactants must be avoided and cone tamination thereof must beprevented to obtain optimum operation, it is necessary to maintain asuitable continuous seal in continuous cata lyss to prevent the flow ofreactants out of the react-ion zone or the flow of the externalatmosphere into the reaction zone, This object is accomplished inaccordance with my invention by passing the catalyst through an inert,non-wetting liquid seal at both'the point of, catalyst in: tro uction toand the point of catalyst discharge from the catalyst chamber. There isthus Drovirei a seal which is not destroyed by the,continuous movementof granular catalyst therethrough.

One of the principal objects of my present invention is to provide agas-tight seal for a chember whereby the uniform and continuous passageof granular material through the seal may be accomplished by means of aconveyor and where'- by different pressure conditions may exist at therespective ends of the conveyor, which pressure lyst and the reactingmaterials continuously fiow T In this way the conditionswill not beinfluenced by movement 9 of the material. 7

Another object of my invention is to provide an improved conveyingapparatus for a. catalyst reaction chamber whereby catalyst may be,continuously fed to and discharged from the chamber without'loss' ofreactants.

. More particularly, my present invention has the advantage of utilizingcommercial conveyors modified only to cooperate with a non-wettingliquid seal so that. a granular catalyticmaterial may be carried intoandout of a reaction zone without allowing egress of vapors orcontaminat-- ing the catalyst.

illustrative thereof, and in'which:

Fig. 1 is a composite elevation and flow dlagram showing onearrangementof the apparatus; Fig. 2 is a partal elevation with certain parts insection on a somewhat larger scale of oneof the conveyors shown in Fig.1;

Fig. 3 is a transverse vertical section taken substantially along theline 3-3 of Fig. 2;

Fig. 4 is an enlarged detail, with parts in section, of some of theflights of the conveyor; Fig. 5 isa horizontal cross sectiontakensubstantiallyalong the line 5--5 of Fig.4; 7 Fig. 6 is. a vertical,substantially central sec tion of a modified forni of conveyor takenalong the line 9-8 of Fig. 7

Fig. 7 is a transverse vertical section taken substantially alongtheline 1-1 or Fig. 6;

Fig. 8 is a substantially vertical section of .a still further modifiedform of construction; and Fig. 9 is a vertical section of another formof In accordance with the preferred form of embodiment of my invention,the catalyst cham ber l0 isnone in which a catalytic reaction is carriedout in the presence of a continuously j .moving catalyst body- Thereactants maybe conveniently fed into the chamber through the feedconduit ll wherein they come into contact withthe continuously movingcatalyst body.) 7 The reacted products may then be conveniently removedthrough outlet pipe l2. For purposes of example only, these reactantsmay be con sidered to be hydrocarbon vapors undergoing conversion in thepresence-ofasuitable catalyst,

which may comprise either a solid catalytic ma- ,.terial such as naturalor synthetic blends containing silica and alumina or a solid impregnatedFurther objects and advantages ot'my inven-- tion will be apparent fromthe following:descrip-' tion "of "preferred forms of embodiment thereoftaken in connection with the attached drawings,

with a catalytic material such as phosphoric acid, at a temperatureinthe range of 750 F. or higher. The specific temperature and the natureof the catalyst are not features ofmy invention but will be well knownfor a particular conversion to those skilled in this art. Pressureoperation is usual and relief valve I4 is thus customarily used.

The catalyst, in accordance with.my invention, substantially fills thetubes l3 through which the reactants pass and is preferably granular andhas a size such that there is only 'suflicient free space between theparticles thereof to permit flow of the reactants through the chamberwith a reasonably low pressure drop. The size of the catalyst particlesis usually relatively large, e. g., in the range of 0.01" to 0.5", sothat they may be readily introduced to and removed from the catalystchamber ,but is also small enough so that adequate surface area forcontact is provided.

The principal feature of my invention is to continuously pass thecatalyst into the chamber l and to remove it therefrom without loss ofreactants or any substantial contamination of the atmosphere within thechamber. The rates of feed to and of withdrawal from the chamber arereadily adjusted so that the quantity of catalytic material within thechamber l0 may be maintained practically constant. In this manner freshcatalyst is continuously fed into the chamber, and spent catalyst iscontinuously withdrawn therefrom and uniform high yields of reactionproducts are accomplished. 1 Each of the conveying operations isindependently carried out by means of an enclosed conveyor whichisprovided with a nonewetting liquid seal, through which the catalyst ispassed and by which the vapors are effectively confined in therespective chambers.

At the commencement of operations, fresh catalyst is initiallyintroduced through the inlet nozzle l5 into the catalyst conveyor,generally indicated at l6, which in turn discharges the catalyst throughthe conduit Il into the upper part of chamber Ill. After passing throughthe chamber l0 and having become fouled and contaminated, the catalystis then removed from the bottomof the chamber through the dischargeconduit [8 into the catalyst discharge conveyor, generally indicated atI9. The catalyst is discharged through the outlet 20, from which itmaypass tov a reactivating chamber 21 for the desired reactivation. Thereactivated catalyst may then be carried by theconveyor 2 2 for returnto the initial catalyst feed nozzle IS in acomplete cycle.

Inasmuch as the catalyst feed. conveyor I6 is substantially the same asthe catalyst discharge conveyor [9, I refer to the latter as shown inFigs. 2 to 5 inclusive as one form of apparatus by means of which thevapor sealis accomplished without interruption of the continuous flow ofthe granular material.

The discharge conveyor is consists primarily 'of two interconnectedU-tubes 24 and'25 which The links 21 have flights 28 of the samesectional shape as the U-tubes; and, as shown in Fig. 5, the flights mayhave internal openings '29 so that they may carry solid matter through aliquid with the liquid falling back as will be hereinafter described.Pulleys 3| and 32, operated by a motor 33, serve to transmit a driving.force to the conveyor.

In operation, as the granular catalyst discharges from the catalystchamber l0 through the discharge conduit 18 into the outer U-tu'be 25 ofthe discharge conveyor I9, it is picked up by the conveyor member 26which continuously moves past the end of the discharge conduit l8. Theconveyor flights 28 engage the catalyst and carry it around the bottomof the U-tube 25 to the discharge outlet 20,

To make these ends of the conveyor path gastight with respect to eachother, I fill the 'U-tube 25 with a liquid material that may beintroduced through surge tank or reservoir 35, which is interconnectedwith the U-tube by pipes 36 and 33a. The liquid will substantially fillthe U- tube 25 and will, by virtue of the pressure difference, seek itsown level therein although the surge tank will reduce the effect ofsudden pressure changes which might flow liquid into a discharge outlet.The movement of the conveyor does not materially disturb the level ofthe liquid.

The liquid used to effect the seal should have certain characteristicsand should be selected with regard to the particular operatingconditions and the particular reaction. It should have a melting pointsufllciently below and a boiling point sufiiciently above the reactiontemperatures so that slight temperature variations within the catalystchamber will not; alter its physical state. It is desirable to usealiquid having a high specific gravity such that the necessary liquidhead to balance the differential pressure can be maintained within areasonable height. The specific gravity of the liquid should preferablybe greater than that of the catalyst so that the catalyst does notaccumulate at the low point of the seal. The liquid should hot wet oradhere to the catalyst particles in any way, and it should not reactchemically with the catalyst; otherwise, the catalytic reaction may notbesatisfactorily carried out, or the activity of the catalyst may be ad--versely affected. It is also preferable that gases dissolve in theliquid to a negligible extent.

The liquid seal may be made in any desired shape but is preferably inthe form of balanced columns as in a U-tube. These columns should havesuch a length that the available liquid head therein is sufficientlygreater than the pressure differential between the catalyst chamber andthe external atmosphere to prevent breaking of the liquid seal bypressure surges. With a U-tube it is especially convenient to usestandard conveyors as the catalyst propelling means.

Certain metals have been found especially suitable as the liquid sealingagent since most catalytic' reactions must be carried out at elevatedtemperatures. Metals having a high specific gravity and a relatively lowmelting point such aslead, are especially useful when the reactionrequires a pressure substantially in excess of atmospheric. Molten leadis also found most satisfactory for use with bauxite and similarclaylike catalysts oftenused in petroleum hydrocarbon reactions. Itsspecific gravity is such that excessive heights of liquid are notrequired to *withstand operating pressures below about V to the catalystchamber I0.

pounds per square inch gauge. Furthermorait does not wet the catalystused; it does not react chemically with the catalyst; and it does notmaterially vaporize at reaction-temperatures in 4 the range of 800-1,000F. Under such. .conditions, the catalytic dehydrogenation,desulfurization, conversion,.or the like of petroleum .hydrocarbons maybe successfully carriedout. Normally liquid materials such as mercury,.other molten metals or molten alloys, and the like may.

. also be used. 7 v

The liquid seal is also maintained in the inner U-tube 24 byinterconnecting the reservoir-35 asthrough pipes 36 and 36b. It isnecessary to have both U-tubes sealed to preventblow through ofv gasesor vapors from the discharge conduit 18 to the discharge outlet 20.vPreferably the openpore the line v53,

l6 or; in the jacket 50 .surrounding the discharge conveyor I9, any:other heat source'such as molten salt may also-be used. The temperatureof: reactivation in chamber 2! is such'that' it is desirable to takeadvantage .of f

the heat as for the, formation of steam. A steam drum- 60 is suitably.connected as by a steam header BI and a downcomer or water connection 62with coils (not shown) in the reactivation chamber 2|. Make-up water issupplied through and. steam is removed through the line-64.

-It may be founddesirable, if any objectionable amount of the liquidforming the seal is carried out on the catalyst, touse a vibratingtrough or similardevice which will slightly agitate .the cattions of theU-tubes are maintained full ofhot I gases and vapors. v This object maybe accomplished-in the section into which the catalyst is dischargedfrom chamber l0 by-leakage of.re-

actants from thecatalyst chamber. :In the section from which thecatalyst is discharged for reactivation, flue gas may be introducedas bymeans of pipes 31; this gas will escape through the outlet into-thereactivation chamber 2].

With reference again to Fig. 1, catalyst is continuously introduced.into the chamber l0;by

means of a similar continuous conveyor 16including the U-tube 40,.whichis provided withthe catalyst inlet 15 and through which the catalyst iscarried to the top of the' conduit IL. In a similar manner a reservoir4| is provided for the non-wetting liquid sealing material, which issimilarly introduced to the outer catalyst conveyor.

tube 40 and the inner U-tube 42 through conduit.

43. The conveyor is similarly operated as by motor 44. As beforementioned, by regulation of the, speed of the respective motors 33 and'44, it. is possible to obtain uniformity of flow .of materialthroughthe catalyst chamber l0.- v g Uniform temperature ,of operation may be,ac-

complished by the circulation of a heating me-) dium in any suitablemanner'by the introduc tion of hot flue gases through the line 45 to theblower 46 and the passage of the gases under pressure. through the line41 The gases may be. withdrawn through the line 48 to thesta'ck (notshown). Another portion'of the heating medium may be introduced throughlines 49 and 49a to the heating jacket 50 surrounding the conveyor [9;the gases may be discharged to the stack as at 5i. Another portion oftheheating medium may be introduced through lines 49, 52,

52a and '53 directly into thetop of the discharge conveyor l9 by meansof the interconnecting lines 31. Still another portion may be introducedby lines 49, 52 and 52binto the jacket-55'surroun'ding the feed conveyor16, from which the gases' catalyst may beremoved through the outlet 16maybe removed to the stack through the line 56."

An additional portion may be introduced through lines 49, 52,52a and 51'to the conveyor 22. Line 58 discharges'fiue gas from conveyor 22' to thestack. By introducing flue gasinto the discharge end 20 of conveyor l9andinto conveyor 22, I am able-to maintain a substantially inertatmosphere therein so that oxidation of the lead by contact of the gaseswith the lead surfaces in both the feed and the discharge conveyors isprevented.

The heating medium for most of this apparatus is preferably flue gasalthough it will be appreciated that, where it is merely circulated.

around a conduit such as in the catalyst chamber ID or in the jacket 55for the feed conveyor alyst and. cause a coalescence of the liquid. Aform of devicewhich may be found useful for such purpose is also shownin .JEig.v 2.. Preferably, i

it is. a relatively shallow anduwide tray .66. which intercepts. thecatalyst as discharged from com 20a for discharge to waste or. to.thereactiyation chamberll as heretofore described.

A modifiedform of conveyor is shown in Figs. j 6 and 7, which devicealso has a U-tube configuration so that a liquid seal can be used.-.Inthis constructiontheconveyor I0- is continuous and -has buckets]!moving in a suitable-housing. 12,-

thelupper part: of which. is interconnected :with

the discharge conduit 13. The-conveyor buckets engage the catalystparticles and carry-themdownwardly to thewell portion 14, which is sub-.

merged in the liquid seaL- Holes 'llla allow the.

liquid to fallback. I

Thewell portion is preferably enlarged at Ma so that the catalyst willfree itself from the conveyor buckets. Because of the difference in thespecific gravity of the catalyst, which is relatively light, and that ofthe sealing liquid, which is usually very heavy, .thecatalystwill risevertically into thedischarge leg l5,.from which the A casing isused tomaintain'the' desired temperature by passage of a suitable heatingmedium I,

thereintoatIB and'removal therefrom at 19. The .conveyoris driven asbyfmotor 80. Prefer ably discharge leg 15 is outwardly flared as shownin order to'prevcnt any'a'rching of the. catalyst,

with consequent plugging of the'leg, as'th'e catalyst rises through theliquid. 7

A stillfurther modified form of construction is shown in .Fig; 8, inwhich the conveyor .82 is mounted in a housing 83 and'is'adapted totransfer a granular material from aco'ndui't 84 inter-'connectedthere'with to-the'well 85, from which thegranular'materia'lwill passupward through the leg 86 under thedifference of density'b etween the granular material and theliquidconstituting the seal,-

In this-case, a rod 81 having'f serrations, teeth,

or projections 88 may=be-provided,"which rodjs' reciprocated byany'suitable means (not shown) to prevent any 'ofthe g ranula-r r'nas'sfrom'arching in leg 86. A jacket 89 tain the temperature:

A still furthermodified 'formof construction is shown in Fig. 9, inwhich a screw form of conveyor' is-used. In this case} the feed conveyoris shown as distinguished from the discharge conm y be used-to main-'-veyors shown in the prior forms'of embodiment of the invention. It alsoconsists of a substantially U-shaped sealingdevice 93 which may beconsidered to be an extension of the feed conduit 94. It is also adaptedto hold a liquid, indicated at 95, for the seal. If desired, theconveyor may also have a jacket 96, to which a heating medium may besupplied,

' The propelling means in this type of construc tion is shown as a screwconveyor 81, which may be driven as by a pulley 98 from any suitablesource of power (not shown). The catalyst, which is fed into theconveyor at 99, is carried downwardly through the liquidlseal by thescrew 91 into the lower portion of U-tube 93. Because of the differencein the specific gravities of the catalyst and the sealing liquid, thecatalyst will rise to-the top of the other leg of the U-tube.Preferably, the screw ll operated by the pulley I02 is provided to aidthe catalyst in its'upward passage through thisleg. The catalyst thenfalls through the feed conduit 94 into the catalyst formed in themovement of the catalyst, the usev of the conveyor elements shown inFigs. 4 and 5 in the conveyor 22 with the introduction of the flue gasfrom line 51 as shown in Fig. 1, will assure the complete carrying awayof 'the'dust particles from the larger granular catalyst, and ifdesired, the dust may be removed by a suitable dust collector I03 orallowed to blow into the at mosphere depending upon its qua'ntity.' This'assures the use of dust-free catalyst in the reaction chamber l0 andthus dust-free reaction products removed in line l2.

It will be appreciated that passage of the catalyst through themoltenmetal seal may also be used to advantage to preheat the catalyst.Temperature conditions throughout the apparatus the depths of liquid inthe respective legs of the U-shaped vessels are changed so that thegreater depth of liquid is in the leg attached to the chamber.

molten metal being non-wetting and chemically inert towards thecatalyst, means to maintain said metal in molten condition, and means tointroduce into said conduits above the molten metal surface aninertgaseous medium to prevent oxidation of the metal.

2. In combination with a catalyst chamber in a reaction zone maintainedat a pressure other than that of a zone external thereto, a gas-tightcatalyst conduit connecting'said zones, a charge of molten metal withinsaid conduit, the conduit being constructed and arranged and the volumeof said liquid charge being correlated therewith to form a head of themetal sufficient to balance the difference in pressure between saidzones and maintain'a' liquid seal therebetween, means to pass a solidgranular catalyst through said conduit and through said liquid seal fordelivery of the catalyst from one of said zones to the other, saidmolten metal being non-wetting with respect to the catalyst, means tomaintain said metal in a molten condition, and means to introduce intosaid conduit, above the surface of the molten metal, an inert gaseousmedium to prevent oxidation of the metal.

' 3. In combination with a catalyst chamber in a reaction zonemaintained at a pressure other than that at a zone external thereto, agas-tight catalyst conduit connecting said zonesrand constructed andarranged to form a U-shaped well, a liquid within said well in a volumesufllcient to charge same to a level above the level of the bend of theU and provide a head sufficient to balance the difference in pressurebetween said zones and maintain a liquid seal therebetween, an endlesschain conveyor to continuously pass a solid granular catalyst throughsaid conduit and through saidliquid seal for delivery of said catalystfrom one of said zones to the other, said duit enclosing said returnreach between said Although I have described preferred forms ofembodiment of my invention, I am aware that other modifications may bemade thereto; and I, therefore, desire a broad interpretation of myinvention within the scope and spirit of the del pulleys and constructedand arranged to form a U within said U-form of the first conduit, 9.gastight housing for one of said pulleys, said housing interconnectingthe upper end of a leg of the second U and the adjacent upper end of theleg of the first conduit which is in communication 1 with the reactionzone; and a charge of liquid in said second conduit to seal the latteragainst passage of gas therethrough.

4. In a system for conducting a contact process and including meansdefining a contact zone whereinfluid is brought into contact with asolid contact material in a divided state, apparatus for transferringsuch contact material between said zone and a zone external thereto andpreventing exchange of gas between the zones, comprising a U-shapedgas-tight conduit for said material, a gas-tight delivery connectionbetween one of said zones and said conduit to pass the contact materialto one of the legs of the latter at a point spaced above the U-bend, theother leg of the conduit having, at a point spaced above the U- bend, anexit for passage of the material into the other of said zones, a body ofliquid within said conduit between said points of admission and egressof the contact material, said liquid being non-wetting and non-reactivewith respect to said material, an endless conveyor extending throughsaid conduit and said seal for passage of said material between saidpoints, a U-shaped gas-tight conduit enclosing-a return reach of saidconveyor and having i'ts legs arranged, opposit'e" the legs of the"first conduit respectively,

gas-tight conduit interconnections between the upper ends of adjacentlegs of said conduits and v forming with said U-shaped conduits anendless conduit" for said conveyor, means within said interconnectionstraining the conveyor for passagethereof between the U-shapedconduits-one of said training means comprising a pulley for driving theconveyor, and a body of liquid within the lower portion of said secondconduit,' said bodies of 'liquid forming seals to prevent exchange ofgas between said zones.

. AUGUST HENRY SCHU'I'IE.

